Expanding Universe question

[Kenyth]

I think that the relationship matter has to itself in it’s various forms is what defines space and time. It’s all relative. I also feel that matter exists and interacts in forms that we have very little or no knowledge of.

In other words, galaxy A is in a universe expanding faster than light only when compared relatively to galaxies B, C, D, etc. In relation to itself, it is stationary.

So the expansion also does not necessarily involve any actual travelling by the matter in question. If the galaxies were indeed travelling greater than the speed of light, that would mean matter is travelling at greater than the speed of light, which we know to be impossible.

urk!

<memory overrun> <error log generated> <underpowered brain rebooting>

[Chronos]

So basically, the space is expanding between the particles, but the atomic forces are keeping the atom together as usual. Yet, there’s the possibility that the expansion of space will eventually hit a breaking point, come a googol or so years, and rip all matter apart at light speed?

Not necessarily a googol years. The Big Rip is actually one of the more potentially imminent End of the World scenarios: Based on current observations, it’s actually plausible that it might happen before the Sun even dies (a matter of a few billion years). If it happens at all, of course: Current observations are also consistent with the much simpler case where the strength of the Dark Energy is constant in time.

But your ruler would always show the sides as 5mm because your ruler would be expanding at the same rate, right?

No, because your ruler is held together by forces (primarily electromagnetism) which, at that scale, are much stronger than anything cosmological. Cosmological effects only show up on scales larger than galaxy clusters (until and unless the Big Rip happens, of course).

[Irishman]

These are impossible concepts.

What is space? It is inherently a component of the universe. So how can the universe be expanding, when there is no there for the universe to expand into? Furthermore, there might be other universes out there, but out where? Not in this universe, but space and time don’t exist outside a universe, so where (and when) is the thingy that these universes exist in, since they don’t overlap?

Analogies don’t help. For the balloon to expand, even if within the skin of the balloon everything expands without a boundary, it is expanding into a dimension that is external to the skin, the 3D space. But cosmologists say the universe defines space, and there is no space outside the universe, so the analogy doesn’t help, because the analogy requires an external space to expand into, and cosmologists say there is no external space to the universe. Except that other universes might be out there.